Antennas

Antennas¶

How EM fields work with Antennas
Good Antenna Designs
Definitions
N1201SA VNA: used to measure how good an antenna is

How antennas work with some basic math https://physics.stackexchange.com/questions/816698/how-many-photons-are-received-per-bit-transmitted-from-voyager-1

Definitions¶

decibels (dB): Is the ration of one signal to another.
- -10 dB is 1/10^th the signal. While -20dB is 1/100^th the signal

dBm: It the absolute value of a signal. 0 dBm is 1mW, 3 dBm is 2mW, -3 dBm is 0.5mW

Power Loss(dB): The Amount of decibels that is lost in the transmission of the data
- This is done by a subtraction because Decibels are logs

Antenna Gain (DBi): This is the measurement of the maximum antenna gain when it is directed correctly instead of using an isotropic antenna
- The higher this number the more directional the antenna is.

dBd: dBd refers to the antenna gain with respect to a reference dipole antenna

Beamforming /MIMO¶

Using multiple Antennas at known locations you can phaseshift the message and create interference waves making areas of higher Signal to noise ratio. (This also makes pockets of lower Signal-to-Noise ratio)

This also works in reverse with the single transmit antenna and two receiving antennas. If you know the phase difference between the two receiving antennas you can shift it back and combine the wave forms together.

Source

Omni-Directional¶

• Good Circular Horizontal Polarization

Yagi Antenna¶

• Good Vertical and Horizontal in a particular Location

Moxon antenna¶

• High Directed
  https://en.wikipedia.org/wiki/Moxon_antenna

https://www.thingiverse.com/thing:2068392
https://www.thingiverse.com/thing:1600088

Log Periodic Antenna¶

• Handel a wide range of frequencies
• Highly directional
  https://oshpark.com/shared_projects/eaS9WNEA

Vivaldi Antenna¶

• Highly Directional antenna
• Range from 1-21 GHz

Helical Antenna¶

- Highly Directional¶

Di-Pole Antennas¶

• Only work well on their residence Frequency
• Their length correlates to the frequency
  • Larger antenna lower the frequency

Turnstile Antenna¶

Quadrifilar Helix (QFH) Antenna¶

V-Dipole Antenna¶

Double Cross Antenna (DCA)¶

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